Puffing apparatus for producing cereal crackers and methods thereof

ABSTRACT

An apparatus for making puffed food products from starch-containing raw materials. The apparatus has a baking and molding chamber defined by several heatable mold elements. The mold elements are individually actuated by direct hydraulic drive systems. The hydraulic power for these drive systems is selectively derived from a common oil pressure supply system which provides continuously high oil pressure to the direct hydraulic drive system for each mold element. The apparatus also has an improved feed system enabling the supply of raw material into the mold cavity such that no material gets spilled and each mold receives an accurate predetermined quantity of raw material.

This application is a divisional of U.S. application Ser. No.10/504,444, filed Aug. 12, 2004, which is a national stage applicationunder 35 U.S.C. §371 from PCT Application No. PCT/EP02/01674, filed Feb.15, 2002.

FIELD

The present invention is related generally to the manufacture of puffedfood-starch containing products which are obtainable from rice, corn,wheat and other cereal grains but also from other starch sourcematerials like potato, beans etc. including mixtures of different foodstarches in any suitable form including grains, broke, grit, flour,pellets and the like.

More particularly, this invention relates to an apparatus enablingautomatic production of low-fat puffed-food products from any ediblestarch source in the form of crackers, cakes, wafers or chips of anydesired shape, thickness, crispiness and taste, and this with remarkablyincreased reliability and efficiency over existing methods and machines.

BACKGROUND

Automatic machines for the making of rice crackers and similar puffed orpopped granular cakes by pressure-baking and expanding a food-starchcontaining material in a heated mold are known from the prior art toexist in a number of distinct machine variants.

Patent documents U.S. Pat. No. 4,328,741 and WO-A-88/00797, forinstance, are representative for machine types using air cylinders forselectively moving upwardly or downwardly an upper baking mold relativeto a movable lower baking mold and to a stationary ring mold, in whichsaid upper mold and lower molds are coaxially receivable in afluid-tight manner and thereby forming a sealed molding cavity. Thesemachines produce a lot of noise and are rather energy consuming;furthermore, air cylinders are bulky devices which often are lessreliable in terms of baking pressure and cracker thickness requirements.

U.S. Pat. No. 5,562,021 discloses a device for preparing puffed foodproducts from cereals such as rice, wherein the cereal is subjected toheat and pressure in a mold cavity, defined by an exterior wall formingan interior surface about the cavity and by a mold piston or punch beingreciprocally driven into and out of the cavity. To avoid the problem ofseizing of the pistons while inside the mold cavity, the said patentproposes a recess of a certain depth and height formed in the interiorsurface of the cavity wall, and to locate therein a cylindrical insertwhich can move or float within the recess. The mold piston is mounted toa pressure plate, whereby an equalizing spring is provided between thetop of the piston flange and the pressure plate. A hydraulic cylinder isadapted to apply pressure to the pressure plate.

U.S. Pat. No. 4,281,593 to Gevaert and U.S. Pat. Nos. 5,102,677 and5,467,693 to Van den Berghe describe pressure-baking apparatusescomprising a hydraulic jack connected with a toggle mechanism fordriving a lower mold or punch upwardly and downwardly relative to afixed upper mold. The patents to Van den Berghe furthermore propose theuse of an annular mold element defining a peripheral wall of a moldingchamber which element is selectively movable relative to the fixed uppermold and also to the lower punch. This facilitates the feeding offood-starch material into a mold cavity and the removal of a puffedcracker from the pressure-baking molding expansion chamber formed bysaid coaxially cooperating upper, lower and peripheral mold elements.

A drawback of said machine types is the use of a toggle mechanismtransmitting hydraulic power to the mold in an indirect way andrequiring special care for aligning mold parts and controlling moldingpressure. In addition a movable peripheral mold is more prone tooverstraining and risk of mold leakage, giving rise to defective crackerquality and appearance after a period of time. In addition, theprovision of a hydraulic jack together with its oil circuit, oil tankand powering motor on each production machine or unit is ratherexpensive.

A generally experienced inconvenience in the production of puffed-foodsnacks by pressure-baking and subsequently expanding a starch-containingcereal or the like mixture in a mold cavity when using currentlyavailable technology is the quantity of trash and waste crackersproduced by puffing machines, which may amount to 10% or even more oftotal cracker output. Further disadvantages of known machines for makingpuffed crackers include the rather long running-in/starting-up timesneeded until a stable production regime is reached and the need offrequently cleaning the baking mold elements. As a result theproductivity and economics of a cracker plant, in particular when makingsmall crackers and chips, may be seriously affected.

SUMMARY

The present invention aims at providing an adequate solution for theproduction problems and technical shortcomings of prior art technologyfor puffed cracker production and in particular at removing theabove-mentioned technical and economical deficiencies of conventionalpuffed-food machinery and plants.

According to the invention in its broadest aspect these objects areachieved by providing one of a plurality of pressure-baking apparatuses,wherein each apparatus has “direct” hydraulic drive means for itsbaking-puffing molds or mold elements and wherein the hydraulic powerfor said drive means is selectively derivable from a common oil pressuresupply line or common rail capable of supplying a constantly andcontinuously high oil pressure to a direct hydraulic drive cylinder ofeach mold element, irrespective of the number of apparatuses or instantpower needs. More in particular, a puffing apparatus is providedcomprising a molding/baking/expansion chamber having upper walls, lowerwalls and side walls defined respectively in an upper baking moldelement, a lower baking mold element and a peripheral mold element,whereby at least said upper and lower mold elements are adapted to beheated and to be selectively moved relative to each other by suitablemeans, and further a slidable feeding plate adapted both fortransporting a predetermined quantity of food-starch raw material intosaid chamber and for pushing outwardly a shaped puffed cracker from saidlower baking mold, the improvement wherein said means for selectivelymoving the upper mold resp. the lower mold comprise an upper hydraulicdouble-acting cylinder disposed on top of to said upper mold resp. alower hydraulic double-acting cylinder attached to the lower side ofsaid lower mold, each of said hydraulic cylinders having a manifold foroil intake and oil outlet mounted directly on the cylinder so as to forman integral part thereof, wherein each manifold is adapted forconnection with a pressure oil feed line and with a return oil line andcomprises four valves, preferably poppet valves, which operativelycooperate for selectively controlling a forward stroke or a returnstroke of the cylinder piston independently in each hydraulic cylinder.From each puffing apparatus the oil is returned through a central returnline, for this purpose teed off at each apparatus and then connected tothe oil outlet of each cylinder manifold, which flows the used oil backto the collection tank of an oil power unit of proper oil capacity andpower output.

In use of the apparatus the four (poppet) valves in the manifoldfunction as follows: a first valve lets the oil in from a centralpressure line in a first oil chamber of the cylinder while a secondvalve lets the oil out from a second oil chamber (at opposite side ofthe cylinder piston) to a central oil return line, whereby the cylinderpiston is moved e.g. in the forward direction over a predetermineddistance. The two other valves, not actuated in the forward stroke, worktogether in a similar way to perform a reverse stroke of the piston.

The pressure oil system of the apparatus is preferably a central systempowering simultaneously a plurality of puffing apparatuses. The systemis outlined for making available a “constant” high pressure in thepressure oil feed line which is branched of to each cylinder manifold ofeach apparatus, and this in spite of different oil flows and/or capacityneeds according to number of puffing machines and actual process cyclefor a given machine.

The power unit of the system comprises an electric motor driving anaxial pump with variable swash plate allowing to create a constanthydraulic oil pressure at varying oil flows or capacities. To ensure aconstant pressure with highest accuracy the system is preferablyprovided with three axial pumps and one accumulator.

Another advantage of the central oil power and pump system is that theoil remains at low and constant temperature. Another pump will functionas an oil circulation pump circulating the oil through a cooling andfiltration unit. In the return line the oil flowing back from eachcylinder manifold is further cooled and may be filtered before flowinginto the oil tank of the system.

The new direct hydraulic drive means for the mold elements in anapparatus according to the invention surprisingly provides considerableimprovements in puffed cracker properties and manufacturing efficiency:a consistently high and constant product quality was achieved, theflexibility to adapt cracker properties w.r.t. composition, texture andshape without risk of burns, seams or desintegration was greatlyincreased. Moreover machine reliability, incl. trouble-free productionruns was remarkably improved. As a result the amount of waste productwas tremendously decreased down to below 1.5% on the average.

The inventor is unaware of a cereal puffing machine ever being developedusing such a direct hydraulic coupling of the movable mould elements. Asa matter of fact, prior art attempts in this direction were discouragedbecause of insufficiently rapid response times of hydraulic cylinderpistons in a situation requiring explosion-type expansion of thecompressed food starch material and highest-speed retraction of a moldelement.

Without willing to be bound by theory it is believed that theexceptional and unexpected puffing process improvements obtainable bythe novel apparatus according to the invention are due to the followingtechnical features:

1) When a command is given to the valves an immediate reaction occurs inthe cylinders because the valves are directly mounted on the cylindersin a manifold thereof and at very close distance to the piston chambers;in addition the preferably used valves are poppet valves which reactvery quickly, i.e. are actuated instantaneously with a command.

2) The hydraulic cylinders are enabled to operate under extremely fastspeed because the driving oil pressure is continuously built-up in thepressure line right at the top of the cylinder. This constant highpressure is released instantly at the moment the poppet valve isactuated. This together results in an attainable mold/cracker expansiontime of down to ten milliseconds, which is extremely short.

3) Both top and bottom cylinders of upper and lower molds areindependently controlled.

According to another aspect of the invention a puffing apparatus isprovided having an improved feed system enabling the supply of rawmaterial into the mold cavity such that no material gets spilled andeach individual mold will receive an accurate predetermined quantity ofstarch-containing raw material selected from grains, pellets, broke,flour etc. incl. mixtures thereof.

According to a further aspect of the invention a puffing apparatus isprovided having an improved ring mold design allowing pressure-bakingand expansion of particularly a plurality of (small) crackers such asmini-snacks, and this without the risk of premature wear or deformationof the ring mold due to heat differential related misalignment betweenthe ring mold cavities and the upper or lower mold punch elementsslidable received in said cavities.

These objects and further embodiments of the invention in many differentforms are defined in the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A-1D are schematic illustrations of the main steps occurring inthe process of making a puffed cracker using a stationary ring mold andrespective upper and lower movable mold elements or punches;

FIGS. 2A-B give side views of a puffing machine arrangement used in thepresent invention for carrying out the process steps according to FIGS.1A-1D;

FIG. 3 is a schematic representation of the oil pressure circuit asconnected with the hydraulic drive cylinders in a puffing apparatusaccording to the invention;

FIGS. 4A-4C give more detailed views of important components in the oilcircuit to power a puffing machine drive system according to theinvention;

FIGS. 5A-5C are cut-away, side views of a raw material feed system forthe puffing apparatus shown in FIGS. 2A-2B;

FIG. 6 depicts details of a ring mold embodiment according to theinvention; and

FIG. 7 is flow chart illustrating a process embodiment of the presentinvention.

DETAILED DESCRIPTION

Referring to FIGS. 1A-1D, important mold position steps in the processof producing a puffed cereal wafer or cracker are shown. The moldcomprises an upper mold 1 and a lower mold 2, both heatable by means ofembedded heating elements (not represented) and movable upwardly anddownwardly by being directly driven by hydraulic cylinders asillustrated and explained below. Upper and lower molds generally havepunch elements (1′,2′) which are slidably receivable in a ring mold 3(preferably fixed but not always required) so as to form therewith ahermetically sealed molding cavity. In FIG. 1A the mold cavity is openand provides a feeding cup for dropping food-starch containing rawmaterial 4 therein by lower mold 2 having been partially retractedwithin ring mold 3 while upper mold 1 is lifted.

In FIG. 1B shows pressure-baking of raw material 4 being crushed,compressed and heated in a closed cavity by descending the upper moldinto the ring mold and then pressurising either one or both of upper andlower molds. The starch in the raw material is gelatinised, becomesamorphous and moisture including chemically bound water of the rawmaterial is driven off and builds up a high internal vapour pressurewhich is suddenly released as shown in FIG. 1C by quickly retractingupper and/or lower punches relative to one another within the ring mold.As a result the compressed raw material explosively expands therebyforming a puffed or popped wafer 5 filling the expansion chamber spacedefined between the upper mold, the lower mold and the ring mold. Asshown in FIG. 1D the upper mold is in a lifted position again, whereaslower punch is moved in the upward direction to raise the cracker to adischarge position flush with the upper surface of the ring mold. Asliding plate of the raw material feed system will push then the puffedcracker from the raised lower mold surface into a discharge chute whereafter the baking-puffing cycle can start anew.

In FIGS. 2A-2B, overall side views of a puffing apparatus are showncomprising a multi-cracker mold, i.e. the upper and lower molds (1,2)include a plurality of die punches (1′,2′) which are slidably receivablein a plurality of corresponding die holes (not shown) of a stationaryring mold 3. Lateral to the apparatus there is mounted a raw materialsupply system 6 comprising a raw material supply line 7 (conduit orhopper) and sliding plates (8,8′) having suitable perforations and backplates to supply a desired amount of grain or pellet material to eachdie cavity of the ring mold. Power means (9,9′,9″), e.g. air cylindersdrive the plates in sliding movements relative to one another and to thering mold. More in particular, a dosage mechanism (8′) driven bycylinder (9′) brings an exact amount of raw material from supply line(7′) into a transport plate (8). Said transport plate is driven bycylinder (9) and positions the raw material precisely over each lowerpunch element (2′) being then in a cup forming feed position, i.e.received partly within ring mold openings (3′). Release plate (8″)driven by cylinder (9″) is then actuated to drop or release raw materialfrom transport plate (8) into said ring mold cups or cavities.

On the back side of each movable mold, i.e. on top of upper mold 1 andat the bottom of lower mold 2, there is mounted an upper hydrauliccylinder 10 and a lower drive cylinder 11, both independently actionablein the upward and downward direction to raise or descend said moldelements over a precisely controlled distance and/or to transmit moldingpressure to the raw material in the mold cavity according to the desiredprocess stages.

Mounting plates (10′, 11′) attached to apparatus frame (12) form supportand fixation members for top and bottom hydraulic cylinders (10, 11) andalso bear and guide the connection thereof with the movable moldelements (1,2). The hydraulic cylinders are powered by a hydraulic oilcircuit illustrated schematically in FIG. 3.

As can be seen from FIG. 3, the oil circuit comprises a high-pressureoil line Pr, powered by a pump unit P, and a return line R flowingreturn oil back to of tank T. The pump unit P is designed to affordcontinuous availability of high-pressure oil at a precise constantpressure in feed line Pr for a sufficiently broad range of desired oilfeed rates. At least one puffing apparatus, generally a plurality ofpuffing machines A1, A2 etc., is connected to the pressure line Pr andthe return line R. In each apparatus high-pressure oil is supplied fromline Pr to upper cylinder C1 and lower cylinder C2 for drivingrespective mold elements schematized by the numerals 1 and 2. Return ordisplacement oil originating from a piston chamber of the double-actioncylinders (C1, C2) is flowed back to return line R. The oil flowrequirements for each cylinder are physically and functionallyintegrated in a manifold M1 of upper cylinder C1, respectively amanifold M2 of lower cylinder C2, which manifolds unite the necessaryoil supply/flow connections including valves needed for the pistonchambers of each cylinder and which is disposed on top of the cylinderbody as a constitutive part thereof.

The functioning of the manifold is depicted in FIGS. 4A-4C for thehydraulic cylinder connected to the upper mold element. The pistonstroke in the downward direction is performed by actuatingsimultaneously poppet valves 1-1 and 1-4. Oil from pressure line Prenters manifold at port P and flows to cylinder port A in upper pistonchamber via valve 1-1. At the same time valve 1-4 is opened to enableback-flow of displaced oil from lower piston chamber through port B tothe return tank line R. During this stroke the valves 1-2 and 1-3 remainclosed. When effecting a reverse stroke in the upward direction thevalves 1-2 and 1-3 are activated such that pressure oil flows from portP via valve 1-2 to port B of the lower piston chamber, whereas at thesame time oil displaced in the upper piston chamber can flow from port Avia valve 1-3 to the tank return line R. At this stage valves 1-1 and1-4 are then closed.

The manifold oil flow line from intake port P to cylinder port A furtherpreferably contains a (over-) pressure valve 2* located between valve1-1 and port A. This allows to regulate the desired molding or crushingpressure for each apparatus individually according to the type andamount of raw material (grains, broke, pellets etc.) fed into the moldcavity, respectively according to the kind of puffed food crackerdesired. In addition a part G may be provided which serves as aconnection for mounting a (safety) manometer.

FIGS. 5A-5C show a particular improvement to the material dosing part ofthe raw material supply system (6) already explained above in connectionwith FIG. 2. In detail, FIG. 5A shows a first position of the neardosing mechanism which is open to the feed fine (7) and is comprised ofa holding or dosing plate (8′) of suitable thickness having therein cupforming dosage apertures; said holding plate constitutes the bottom ofraw material feed conduit (7) and its top and bottom surfaces aredelimited by upper and lower perforated plates (8*,8**) which arearranged to slide together parallel to dosimeter plate (8′) whenactuated by cylinder means (9′). The position of perforated plates(8*,8**) as depicted in FIG. 5A enables the dosage apertures or cups tobe filled with starch-containing raw material. In FIG. 5B the perforatedplates are shifted to the right thereby closing the dosimeter cups tothe raw material entry side but at the same time opening the cup bottomtowards a transport plate (8), in fact a second apertured holding platecooperating with a perforated back plate (8″), whereby the raw materialcontent of the dosimeter cups in plate (8′) is then released—within aclosed environment—with maximum accuracy in (preferably wider)openings/cups provided in transport plate (8), having a holeconfiguration similar to that of the dosimeter plate and of the ringmold cavity pattern. By actuating drive means (9) and (9″), cf FIG. 2,the raw material is transported to the ring mold position and dropped inthe respective mold cavities (3′). Thus the provision of aholding/dosimeter plate (8′), combined with perforated sliding plates(8*,8**), “in addition” to a conventional dosing or holding/transportplate system (8,9; 8′,9′) allows a constantly more accurate supply ofprecisely metered quantities of raw material to the mold cavitieswithout any losses or spill over of granular or other material which isnormally unavoidable in conventional feeding slides of puffing machines.

FIG. 6 shows an improvement in the design of the peripheral mold or ringdie wherein the upper and lower punches (1′,2′) of the movable moldelements must be slidably received in a fluid-tight manner. The ringmold, for instance for a multi-cracker die (e.g. 64 mini-cakes of 25 mmin diameter), comprises a die mounting plate containing a plurality ofdie holes which is stationary by being fixed to the vertical frame posts(1,2) of the apparatus, about midway between upper and lower supports(10′,11′) of the hydraulic drives (10,11). Each die hole includes aninternal sleeve or a bushing that is elastically mounted to die hole anddie plate, such that in use the bushing has a self-aligning or-centering property within the die hole relative to the slidablyentering punches. The elastic mounting may be realized by retainingrings or circlips (circular and small die holes) and by screwablefastening elements (bolts and nuts, etc.) for large dies and polygonalshapes. The self-aligning die bushings prevent wear, damage andpremature failure of dies or punches, incl. production interruptions dueto possible misalignments caused by temperature and thermal expansiondifferences between die and punch components.

The apparatus according to the invention is furthermore veryadvantageous in terms of process monitoring, controls and adjustments.As a matter of fact the high precision and quick response of the novelhydraulic drive system makes it easier to control the process steps,since all process movements and piston displacements are controllable interms of time units resp. actuation times of valves in the oil manifold,without need of electromechanical contact, relay or stop means. Inpracticing the invention, all process movements, cf. FIG. 1, and processtemperatures are controlled by a PLC, e.g. a central PLC for a pluralityof puffing machines, and are visualized (or selectively visualizable foreach connected machine) on a monitor screen or control panel. Theprocess control system comprises the following features and/or steps:

Baking Temperature:

lower mold platen temperature

upper mold platen temperature

Process movements (see also FIG. 7):

1. Cup time: bottom cylinder retracts (goes down) and retracted punchesof lower mold form feeding cups within ring mold dies to allow the rawmaterial to be dropped in mold.

2. Start time: top cylinder extends (goes down) and upper mold punchgoes down inside ring mold die.

3. Press time: bottom cylinder extends and lower mold punch is displacedupwardly, compressing the raw material between the two punches.

4. Bake time: all valves remain closed, both cylinders and punches arekept stationary.

5. Top expansion: top cylinder retracts.

6. Bottom expansion: bottom cylinder retracts (mostly) simultaneouslywith top cylinder.

7. Expansion delay: delay time of expanded/puffed product inside theretracted punches or expansion-opened molds to allow shape control offinished product.

8. Thickness control: bottom cylinder extends and recompresses alreadyexpanded product to a given extent, thereby controlling shape, thicknessand surface flatness (optional).

9. Out time: top cylinder retracts upper mold above ring mold and bottomcylinder extends so that lower mold punch pushes finished product out ofring mold.//Thereafter the cycle starts anew with step 1 including thesupply of starch-containing raw material into the mold cavities.

The above process parameters are simply optimised by empirical testing,trial and error and easily adjustable according to raw material kind,cracker type (shape, thickness, . . . ) and desired cracker propertiessuch as texture, crispiness etc.

The direct hydraulic drive of the puffing molds in the new combinationof super fast actuation of cylinder pistons and continuous availabilityof a constantly high oil pressure from a common or central high pressureoil line enables the above testing, optimisation and control to becarried out in conditions of increased accuracy, flexibility andreliability and this in much less time than previously possible. Thisalso applies to industrial cracker production in terms of crackerquality and waste generation.

Since a big number of puffing machines are connectable to said centraloil line, the new system of puffed cracker manufacture may give rise tosubstantial savings in power consumption and equipment costs, especiallywhen running a large-scale cracker plant.

Although particular embodiments and working modes of the invention havebeen illustrated and described, it is clear that numerous modifications,applications and combinations are possible without departing from thekey teaching of the invention. In this connection the extent ofprotection is only limited by the scope of the following claims.

1. A system for producing food products from starch-containing rawmaterials which are subjected to pressure and heat with one or morepressure-molding apparatuses, each of the pressure-molding apparatusescomprising: (a) at least one heatable mold cavity comprising astationary mold element having an interior peripheral wall about thecavity; (b) at least one punch movable into and out of the cavity anddriven by a double-action hydraulic cylinder operatively connected tothe punch; and (c) a central oil pressure generator system comprisingone or more axial piston pumps of the variable displacement typeincluding a swashplate allowing a stepless variation of oil flowincluding continuous pressure control and compensation for keeping oilpressure constant irrespective of operatively used oil, central pressureoil generator system further comprising an oil tank for receiving returnoil from the hydraulic cylinder by the return line, wherein thehydraulic cylinder comprises a manifold directly mounted onto a headportion of a cylinder body, the manifold has connections with a feedline of pressure oil and a return line of operatively displaced oil, themanifold houses a plurality of oil circuit channels and actuable valvesdesigned for selectively and instantly applying hydraulic oil pressurefor a given time duration to an upper or lower piston compartment of thehydraulic cylinder, thereby simultaneously moving a cylinder piston overa desired stroke length in a direction required for pressure-baking thestarch-containing raw materials.
 2. The apparatus of claim 1 wherein atop wall of the mold cavity is defined by an upper punch driven by anupper hydraulic cylinder and a bottom wall of the mold cavity is definedby a lower punch driven by a lower hydraulic cylinder, the upper andlower punches being separately movable in and out of the cavity.
 3. Thesystem of claim 1 wherein the stationary mold element comprises aplurality of mold cavities cooperating with a corresponding plurality ofupper punches and lower punches, the upper punches being disposed on anupper punch plat connected to an upper hydraulic cylinder and the lowerpunches being mounted on a lower punch plate connected to a lowerhydraulic cylinder.
 4. The system of claim 3 wherein the manifold ofeach of the upper and lower hydraulic cylinders further comprising aninternal oil channel circuit including a main inlet port communicatingwith the feed line, an outlet port communicating with the return line,an internal oil port for direct pressure oil supply to an upper pistoncompartment and an external oil port communicating with an inlet/outletport of a lower piston compartment of the hydraulic cylinder body, whichoil circuit has valves which are integrated in the manifold so thattheir controlled and selective actuation from a control unit, thecylinder piston will instantly perform a stroke of precise length andduration.
 5. The system of claim 1 further comprising a plurality of thepressure-molding apparatuses, wherein each one of the pressure-moldingapparatuses is connected to the feed line and to the return line.
 6. Thesystem of claim 1 wherein the mold element comprises a stationary dieplate having at least one aperture with a ring die element disposedtherein, the ring die element being mounted in the aperture such thatself-aligning of the ring die element is ensured when the punch isdriven into and out of the mold cavity.
 7. The system of claim 6 whereinthe ring die element is fastened in the aperture.
 8. The system of claim6 further comprising a plurality of the apertures in the stationary dieplate, each of the apertures with one of the self-aligning ring dieelements disposed therein.
 9. The system of claim 4 wherein the manifoldfurther comprises a flow control valve for adjusting oil flow to thehydraulic cylinder.
 10. The system of claim 1 wherein the central oilpressure generator system further comprises an accumulator device thatensures a constant high oil pressure is stably maintained in the feedline.
 11. The system of claim 1 further comprising a feeding system forsupplying a metered amount of the starch-containing raw materials intothe mold cavity, wherein the feeding system comprises: a dosimeter platewith openings defining starch material feed cups; and two aperturedsliding plates located parallel to and at opposite sides of thedosimeter plate, wherein the two apertured sliding plates areindependently actuatable for sliding displacement by being connected toseparate actuation system.
 12. The system of claim 6 wherein thestationary die plate is detachably disposed on die plate supports.
 13. Asystem for producing food products from starch-containing raw materialswhich are subjected to pressure and heat with one or morepressure-molding apparatuses, each of the pressure-molding apparatusescomprising: (a) at least one heatable mold cavity comprising astationary mold element having an interior peripheral wall about thecavity, the stationary mold element comprising a plurality of moldcavities cooperating with a corresponding plurality of upper punches andlower punches, the upper punches being disposed on an upper punch platconnected to an upper hydraulic cylinder and the lower punches beingmounted on a lower punch plate connected to a lower hydraulic cylinder;and (b) at least one punch movable into and out of the cavity and drivenby a double-action hydraulic cylinder operatively connected to thepunch; wherein the hydraulic cylinder comprises a manifold directlymounted onto a head portion of a cylinder body, the manifold hasconnections with a feed line of pressure oil and a return line ofoperatively displaced oil, the manifold houses a plurality of oilcircuit channels and actuable valves designed for selectively andinstantly applying hydraulic oil pressure for a given time duration toan upper or lower piston compartment of the hydraulic cylinder, therebysimultaneously moving a cylinder piston over a desired stroke length ina direction required for pressure-baking the starch-containing rawmaterials, the manifold of each of the upper and lower hydrauliccylinders further comprising an internal oil channel circuit including amain inlet port communicating with the feed line, an outlet portcommunicating with the return line, an internal oil port for directpressure oil supply to an upper piston compartment and an external oilport communicating with an inlet/outlet port of a lower pistoncompartment of the hydraulic cylinder body, which oil circuit has valveswhich are integrated in the manifold so that their controlled andselective actuation from a control unit, the cylinder piston willinstantly perform a stroke of precise length and duration, the manifoldfurther comprising a flow control valve for adjusting oil flow to thehydraulic cylinder.